There are numerous reasons that you may want to have raised beds and there are also various ways that they can be built. There are some great pre-built kits out there, but we are going to look at how to build raised bed vegetable garden ourselves. There are all sorts of materials that you can use for your raised bed, including timber, wicker, brick and more. Here at the Garden Doctor, we like to build our raised bed vegetable garden from timber and that is what we will show you in this article, although if you are using another material, that will be fine, you can still read on and see how to do that too!

Raised Bed Growing Vegetables
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Why Build a Raised Vegetable Garden?

Raised beds are a great way to manage your vegetable growing. Not only are they beneficial for people with mobility problems, but it is also true that having a raised bed vegetable garden will keep your plants healthy and extend the growing season by keeping the soil warmer for longer. We also like the fact that one of the main benefits of raised garden beds is that you have more control over the quality of your soil. Many gardens do not have ideal soil for growing vegetables as many gardens have soil that is too sandy or full of clay. Clay does not drain well which can cause roots to suffocate and rot, and sand is not great for your vegetables because it does not hold any nutrients which can cause your plants to starve.

Another positive of having quality soil is that it will help you control the little pests and other nasties that may affect your plants.

Very High Raised Bed
Very High Raised Bed

What to Think About Before Building a Raised Bed Vegetable Garden?

Although building a raised bed is pretty straightforward, before you think about how to build a raised bed vegetable garden, there are a few things that you will need to consider. You will need to consider the space that you have available in the sun, your height requirements, and your budget.

Space

The beauty of making your own raised bed is that you can build it to your own specifications to make it fit wherever you need it to. You will need to consider the width of your bed as you will want to reach all areas without having to stand on the soil and that includes thinking about how you are able to access the bed for watering and pruning etc. If you are limited on space you can build your raised bed to any size that you want, you can make small squares or L shapes to fit in a corner or you could build a long and thin bed that will look great as the border to your garden.

If you are not limited on space or have your own allotment, you will have nothing to worry about and if this is the case, we recommend making 3 raised beds which gives you the opportunity to rotate your crops.

Height

Before building, you should think about how high you want to build your raised bed. Do you want to keep your plants out of the reach of children or nosy pets? Do you have mobility issues that may prevent you from bending down for any period? Or do you simply prefer the aesthetic of a certain height over another? There is no maximum height for a raised bed if you can reach all the plants that you are tending but there is a minimum height, and this is due to the depth of your soil. You will not want to have a raised bed for your vegetables that are less than 18-inches (especially if growing Potatoes).

Materials

Choosing the right material for your raised bed is crucial not only for its durability but also for the health of the plants you intend to grow. Different materials have their own advantages and disadvantages, and your choice will largely depend on your budget, aesthetic preference, and the longevity you desire for your raised bed.

  • Wood: A popular choice due to its natural look and affordability. Cedar and redwood are naturally rot-resistant, making them ideal for raised beds. However, wood can deteriorate over time, especially if it’s not treated or if it’s in constant contact with moist soil.
  • Stone or Bricks: These materials are durable and can add a rustic or polished look to your garden, depending on the type of stone or brick you choose. They are, however, more labour-intensive to set up and can be on the pricier side.
  • Concrete Blocks: Durable and relatively affordable, concrete blocks can be used to create a modern-looking raised bed. Ensure that the blocks haven’t been treated with harmful chemicals that might leach into the soil.
  • Galvanized Steel or Metal: These materials are durable and can give your garden a sleek, contemporary look. They heat up quickly, which can be beneficial for plant growth in cooler climates but might not be ideal for hotter areas.
  • Recycled Plastic or Composite: These are rot-proof and can last for years. They are a good choice for those looking for an eco-friendly option, but they might not offer the same aesthetic appeal as natural materials.
  • Natural Logs: For a rustic look, using logs can be an attractive choice. They are, however, susceptible to decay over time.

When choosing materials, also consider factors like:

  • Soil pH Levels: Some materials can alter the pH level of your soil. For instance, concrete can make the soil more alkaline.
  • Chemical Leaching: Treated woods or certain metals might release chemicals into the soil, which can be harmful to plants and humans.
  • Maintenance: Some materials might require regular maintenance or treatments to prolong their life.

Budget

Building your own raised bed vegetable garden is relatively inexpensive but it is not only the cost of the building materials that you must think of; you will have to think about the cost of the topsoil, compost, and whatever else you choose to fill it with.

Raised Bed Made of Brick
Raised Bed Made of Brick

How to Build Raised Bed Vegetable Garden

For the purposes of this article, we are going to show you how to build a raised bed vegetable garden that is (L)8’ x (W)4’ x (D)18” and we will use a technique that can be easily scaled for any dimensions that suit you.

You Will Need

  • 6 lengths of untreated timber (L)8’ x(W) 6” x(D) 2”
  • 6 lengths of untreated timber (L)4’ x(W) 6” x(D) 2”
  • 4 untreated timber posts (L)18” x (W)4” x (D)4”
  • 48 x 3” Deck Screws

Step 1. Consider Position and Height

As we mentioned earlier, by now you will have decided on where you want your raised bed to go and its height. Hopefully, you will have levelled the ground as having level ground not only makes building the raised bed easier but will also help make it last longer as there will be less stress on the wood and joints.

Step 2. Build the Base Frame

  • You will build the frame by attaching 2 of your timber posts to the end of one of the 4’ lengths of timber making a U shape.
  • Repeat with the other 2 posts and another 4’ length. Now you will have 2 U shapes.
  • With the posts inward, you will want to attach the 2 ends with the longer 8’ boards making a rectangle.

Step 3. Finish the Frame

Now you have the base of the frame you can stack the other boards appropriately.

Raised Bed Vegetable Garden Diagram

Step 4. Fill your Raised Bed Vegetable Garden with Soil

Now you have the frame for your raised bed vegetable garden completed, you will need to fill your new frame with soil. What you choose to fill your raised bed with is especially important for your vegetables.

Best Soil Mix Raised Bed Vegetable Garden

There are a whole load of different mixes and compositions that different gardeners will swear by and all can be successful with the right amount of feeding and cultivation but we believe that the best soil mix for a raised bed vegetable garden is 60% screened topsoil, 30% compost and 10% potting soil.

60% Screened Topsoil

Screened topsoil is available for delivery from most builder’s merchants and will come in handy tonne bags which will save you and your car bringing loads back from the garden centre. Good quality topsoil will be free of any lumps or large stones making it easier for tilling and planting your new crops.

30% Compost

Compost or well-rotted manure will be available at many farms and it is quite inexpensive. At the Garden Doctor, we like to make our own compost but do not worry if you cannot do that, farm bought compost and manure is fine. This is our organic matter that will provide our vegetables with plenty of nutrients.

10% Potting Soil

Potting soil is not technically soil at all. Potting soil or potting mix as it is known is a mixture of peat moss, perlite and/or vermiculite. Potting soil is a porous material that will aid in the drainage of your soil.

Freshening the Soil in a Raised Bed
Freshening the Soil in a Raised Bed

How to Fill Your Raised Bed Vegetable Garden?

Once you have decided on the right soil mix for your vegetable garden, you will have to think about adding it to the garden. Our gardens are placed in an area that drains well so we do not have to worry about adding any sticks or shingle to the bottom of the bed. We also fill our beds in the autumn so that we are able to put as many fallen leaves as we can into the lower levels of our soil. You can add the ingredients to your mix however you wish but we like to line the bottom with a thin layer of compost and then we will give the rest a good tilling so it is all mixed nicely. 

Common Concerns about Raised Bed Gardening

Building on Hard Surfaces

Many gardeners wonder if they can establish raised beds on hard surfaces like patios, concrete, or driveways. The good news is that raised beds are versatile and can indeed be built on these surfaces.

There are a few considerations to keep in mind:

  • Ensure proper drainage to prevent waterlogging. This can be achieved by adding a layer of gravel or broken pottery at the base.
  • Using a permeable landscape fabric at the bottom can also help with drainage and prevent the soil from mixing with the gravel.

Potential Fungal Growth

Raised beds, due to their structure, can sometimes retain more moisture than traditional garden beds. This can lead to concerns about fungal diseases, especially in areas with high humidity or prolonged wet seasons.

Here’s how to mitigate this concern:

  • Ensure the soil mixture is well-draining. Incorporating compost, sand, or perlite can improve soil drainage.
  • Avoid overwatering. It’s essential to monitor the moisture levels in the soil and water only when necessary.
  • Regularly inspect plants for signs of fungal diseases, such as discoloured leaves or mould growth. Early detection and treatment can prevent the spread of the disease.

Material Durability

Given the investment in setting up raised beds, gardeners often worry about the longevity of the materials used. If using wood, opt for naturally rot-resistant varieties like cedar or redwood. Regular maintenance, like sealing or painting, can also extend the life of wooden raised beds. Alternatively, consider using more durable materials like stone, brick, or galvanized steel.

Conclusion

There you have it; this is how to build a raised bed vegetable garden. It may seem like a lot of hard work but in reality, it is far easier to build and manage than just digging up the garden. Hopefully, you will have read this and be confident enough to give it a go yourself or even get the kids involved and help them learn and see the whole process from starting the bed, all the way to eating the veg! There are also many other ways to build your vegetable garden as we mentioned earlier. If you are building one in the garden, you may want to build it with bricks as they will be more aesthetically pleasing, or you may like to recycle and want to build one with some old, corrugated iron. The choices are endless. If building one seems like it is too much hard work, you could always buy one here! (Amazon link – opens in a new tab).

Things to Consider When Building Raised Beds Infographic

Garden Doctor Tips

“Make sure to use untreated or old timber if you are building the raised bed for vegetables. Treated timber is OK if used for flowers or ornamental plants!”

“Build your raised bed vegetable garden in the Autumn so you can add fallen leaves to the lower levels of the soil!”

“Keep a healthy compost bin throughout the year and fill it with organic matter to add to your raised bed!”

“If your raised bed vegetable garden is on concrete or a base that has little or no drainage, put a layer of shingle in the bottom!”

Frequently Asked Questions

What do you put in the bottom of a raised garden bed?

If the location of your raised bed has very little or no drainage, it is good practice to have a good 2-inch layer of stones or shingle in the bottom to allow any excess water to drain from the soil. Soil that is too wet can damage the roots of your Vegetables and make them rot.

Climate is also important as in warmer climates you may want to add a liner to the bottom to hold water. If the location of your raised garden bed has good drainage and is on a level surface, I wouldn’t add anything to the bottom so that worms can come and go as they please. 

Best size for raised garden bed?

There is no best size that will apply to everyone. A lot of people will have different requirements and will build their beds to suit them. You will need to consider your accessibility for tending, pruning and watering.

Our preferred size for a raised garden bed is 8′ x 4′ x 18″ and to ensure good crop rotation, we have 3 of these together.

How much space for a raised vegetable garden?

As much space as you have available. 

If you are just beginning, you can start small and as you become more confident, you can scale it up to whatever suits you!

How deep should my raised garden bed be?

For most flowers and ornamental plants, 6-12 inches will be adequate although most vegetables will require approximately 12-18-inches of soil. 

For our vegetables, we never go below 18-inches.

Where can I build a raised bed?

You can build your raised bed anywhere although you will have to consider the warmth and light that the bed receives. 

You will also need to consider your access to the bed so that you can look after your plants.

What is the best mulch for vegetable gardens?

Leaves & Grass Clippings. The best mulch for vegetable gardens is a mixture of chopped leaves and grass clippings. 

Chopped leaves and grass clippings are great organic mulch that will not take too long to decompose and add nutrients to your soil. 

They also make a great insulator, keeping the soil warm and also keeping those pesky weeds at bay. 

How do you mulch a raised garden bed?

Add approx 2-inches of mulch material to the top of your soil keeping a 2-inch space around the stems of your plants to reduce the risk of fungal infections and disease contamination.

We prefer to use organic matter like chopped leaves and grass clippings but there are other things like plastic sheeting and straw that are also widely used. 


Author

Trevor Wright is not just a seasoned horticulturist; he’s the esteemed Garden Doctor. With a BSc in Horticulture and years of hands-on experience in the soil, Trevor has become a trusted mentor for all things gardening. As the founder of Garden Doctor, he’s committed to clarifying the intricacies of gardening, offering straightforward advice that’s rooted in years of practice. His writing is a garden of how-tos, savvy insights, and comprehensive guides that enable individuals to nurture and grow their garden dreams. When he’s not knee-deep in garden beds, Trevor is at his keyboard passing on his green-thumbed wisdom to budding gardeners, ensuring that the legacy of sustainable and joyful gardening blossoms far and wide.


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